MICROMORPHOLOGICAL STUDY ON THE LEAF EPIDERMIS OF Schizostachyum nees FROM VIETNAM

Table 1. Taxa and voucher for species sequenced in this study

III. RESULTS

The foliage leaf epidermis of 13 species of Schizostachyum investigated (fig. 1 – 5). It seems to be made up of the forms of short cells, long cells, midrib of the leaf blade and silica bodies are more conspicuous when examined with SEM similar to the results of previous studies (Metcalfe, 1956, 1960; Tateoka, 1959; Wu, 1962; Clark, Londono, 1991, Chen et al., 1992). In case of the genus Schizostachyum, epidermal cells are highly modified and become quite different in appearance from the original cell. These characters are important in classification such as: hairs – microhairs and palliate forms; and distributional patterns around the stomata apparagus of the abaxial and adaxial foliage leaf epidermis (Wu, 1962; Yang et al., 2008). They are presented in table 2 and figure: 1 – 5.

3.1. Hairs – Microhairs

Hairs – Microhairs commonly seen and consist of three types such as long hairs, geniculate hairs, and spines:

3.1.1. Long hairs (L)

Long hairs are narrow, long and one celled hairs. They are usually found on the epidermis covers but widely distributed over the completely lower epidermis of some species (S. funghomii, S. nghianum, S. hainanense, C. langbianense, S. ninhthuanense and S. yalyense). However, long hairs are abundant in S. yalyense.

3.1.2. Geniculate hairs (G) (bicellular hairs)

Geniculate hairs arise from the derivatives of the short epidermal cells (Wu, 1962), which are usually broken off by external forces and distributed on the lower epidermis covering the sclerenchyma region. They situated on the lower epidermis of some species (S. sp2, S. sp3, S. hainanense, S. langbianense, S. ninhthuanense, S. pseudolima, s. mekongense and S. yalyense). However, long hairs are abundant in S. yalyense.

3.1.3. Spines hairs (S)

Spines hairs are short, spine – like cells, which are rounded at the base and acute at the apex (Wu, 1962). They are usually dense present on both surfaces over sclerenchyma region in some species (S. hainanense, S. langbianense, S. ninhthuanense, S. mekongense), but sparse in S. yalyense, S. funghomii and S. pseudolima.

3.2. The stomata and papillae

The stomata of all species on the lower epidermis are larger, elliptical in shape and arranged in 2 – 5 rows on each side of a vein. Each stoma covers finger – like protuberances (papillae) which come forth from the epidermal cells next to the epidermal cells, incline towards the center of stoma (Wu, 1962). There are obvious variations in papillae forms and distributional patterns around the stomatal apparatus amongst the examined genera, and their significance is to indicate taxonomic value (Wu, 1962; Yang et al., 2008). There are usually four triangular papillae overarching each individual stomata apparagus in all species, but otherwise, S. langbianense, S. aciculare, characterized by having four triangular papillae overarching each individual stomata apparatus and surrounded. However, four triangular papillae overarching each individual stomata apparatus are unequal in length amongst species. There are two types:

– The triangular papillae overarching are surrounded, which found in S. dullooa, S. nghianum, S. ninhthuanense and S. yalyense;

– The triangular papillae overarching are long, which found in some other species.

In addition to the papillae, the number of rows of stomata is also worth noting (Wu, 1962). On the lower epidermis in Schizostachyum, the number of rows of stoma varies from 2 to 5 rows on each side of a vein and depends on the species. The number rows of stoma can be divided into 4 patterns:

In some case, there are 4 – 5 rows found in S. yalyense and S. ninhthuanense.

In some case, there are 4 – 5 rows found in S. sp2, S. sp3 and S. mekongense.

In some case, there are 3 – 4 rows found in S. funghomii, S. sp2 and S. langbianense.

In some case there are 2 – 3 rows found in S. hainanense, S. pseudolima.

3.3. Discussion and conclusion

Wu (1962) shown about the variation in occurrence and distribution of microhairs. It is important to know whether the walls of the basal cells of microhairs are smooth. The leaf epidermal characters of Schizostachyum species in general, and the papillae form and distributional pattern on the adaxial foliage leaf epidermis have been proven to be of

taxonomic value at the specific, generic (Metcalfe, 1960, Yang et al., 2008). In the current study, epidermal features were again constant within species. Schizostachyum species were confirmed that each individual stomatal apparatus is overarched by four branched of unbranched triangular papillae (Yang et al., 2008). However, four triangular papillae overarching each individual stomata apparatus are unequal in length amongst species, as discussed above.

These are important in classification such as hairs – microhairs and palliate forms and distributional patterns around the stomata of the abaxial foliage leaf epidermis. Thus, with the possible combination of several vegetative and anatomical characteristics, an experienced anatomist could succeed in identifying the species of Schizostachyum.

Acknowledgements

The authors would like to express their sincere thanks to Vietnamese Academy of Forest Science and Foundation of China (grant no. 30770155), South China Botanical Garden for supporting collected specimens and the investigating scanning electron microscopy.